A/c Only Works For About 12 Hours, And Only Blows Cold Air Out Of One

[abbalong83]

I have a 1991 LS400. The a/c worked fine until about a year ago. I have taken this car to so many shops (including Sewell) and have not found an answer or solution to my problem. You can imagine, I am going on over $1,500 in diagnostic fees.

When I vacuum out and recharge the a/c, it only lasts for a total of 12 hours or so. Even when fully charged, it will only blow out cold air from the center front vent (right). All other 5 vents are hot air. That one vent, blows freezing cold air.

I am guessing these issues are 2 seperate issues. However, the only "diagnostic" I am getting is "There's no codes, but it's the compressor." So I ask what exactly is wrong with it? It turns on and blows cold, (for a short time) just fine. From the outside, there is no dye anywere indicating a leak. When I ask if a new compressor will fix the problem, I get "Dunno, we gotta change it to find out."

Now, I know, I know, being a female brings most of this on.

I just want it fixed. I was deeply saddened that not even the mechanic at Sewell Lexus could give me an answer, especially since my car had all of the repairs done there, before I bought it.

Any advice will be helpful. I have had friends suggest replacing the hoses (lines). Labor on that is kind of steep and most places I have talked to refuse to do it without replacing the compressor too.

[1990LS400]

The early LS400 A/C compressor was apparently not as reliable as the later ones. By the time I sold my 90 LS400 in 2003 after driving it from new, it was on at least its 3rd A/C compressor ... I think it was on it's fourth. The orginal one failed the first summer I had the car - a memorable experience as we were all dressed up and driving to a wedding on a hot Saturday afternoon.

I agree you have multiple issues. That the cold air is coming out of only one vent seems to indicate a problem in the system that opens and closes the dampers in the HVAC ducts. I don't have much knowledge about how the system works but based on the noises in my 90 LS after the engine was shut off, it sounded like the HVAC duct dampers were driven by vacuum.

Is your A/C losing refrigerent? If it is, it should be pretty easy for a mechanic to find the leak by adding dye; I've had that done several times on both my LS400's although a slow leak might mean you have to return to the mechanic after a few days for him to check for the leak with a black light.

Is your A/C still running R12 refrigerent or has it been converted to R134a. I had mine converted the last time I bought a new A/C compressor although thereafter I had to have it recharged every year or so - but R134a refrigerent is cheap compared to R12. I don't know what conversion kits cost these days. The total cost of conversion, not including another new A/C compressor, was something like $300-$500 12 to 14 years ago.

It may be getting time to replace this car and maybe buy one new enough to have orginally come with an R134a system. Maybe your mechanics are a bit disinterested in fixing this because of the car's age and value. It shouldn't be this way but I sensed that kind of disinterest at the local Lexus dealer well before I sold my 90 LS in 2003. They seemed more eager in selling me another new LS than fixing my old one.

I don't know if it will help but the following webpage has a link to informaiton on how to read HVAC problem codes in a 90-94 LS: http://www.lexls.com/tutorials/air/

[pj8708]

The early LS400 A/C compressor was apparently not as reliable as the later ones. By the time I sold my 90 LS400 in 2003 after driving it from new, it was on at least its 3rd A/C compressor ... I think it was on it's fourth. The orginal one failed the first summer I had the car - a memorable experience as we were all dressed up and driving to a wedding on a hot Saturday afternoon.

I agree you have multiple issues. That the cold air is coming out of only one vent seems to indicate a problem in the system that opens and closes the dampers in the HVAC ducts. I don't have much knowledge about how the system works but based on the noises in my 90 LS after the engine was shut off, it sounded like the HVAC duct dampers were driven by vacuum.

Is your A/C losing refrigerent? If it is, it should be pretty easy for a mechanic to find the leak by adding dye; I've had that done several times on both my LS400's although a slow leak might mean you have to return to the mechanic after a few days for him to check for the leak with a black light.

Is your A/C still running R12 refrigerent or has it been converted to R134a. I had mine converted the last time I bought a new A/C compressor although thereafter I had to have it recharged every year or so - but R134a refrigerent is cheap compared to R12. I don't know what conversion kits cost these days. The total cost of conversion, not including another new A/C compressor, was something like $300-$500 12 to 14 years ago.

It may be getting time to replace this car and maybe buy one new enough to have orginally come with an R134a system. Maybe your mechanics are a bit disinterested in fixing this because of the car's age and value. It shouldn't be this way but I sensed that kind of disinterest at the local Lexus dealer well before I sold my 90 LS in 2003. They seemed more eager in selling me another new LS than fixing my old one.

I don't know if it will help but the following webpage has a link to informaiton on how to read HVAC problem codes in a 90-94 LS: http://www.lexls.com/tutorials/air/

(Nice job Jim!)

[abbalong83]

Thank you for the reply! Yes, I have had it converted to R134a. The dye is not visible anywhere, which is confusing to me. I even got under there myself after insisting on the blacklight and glasses at the shop. Nada. I am floored as to what it could be. Could it be possible that it has an internal leak that cannot be seen from the outside?

I was thinking the same thing about the "flappy thingies" (<-- woman talk for the dampers) because I took out the center dash, radio and all, and noticed that there was a flap or something not closed and the cold air was hitting it and bouncing straight to the vent that blows cold. I will research this issue tonight, being that it seems to make sense (to me anyways) to try and fix this issue in the meantime.

I will update when I find some answers.

Thanks again!!!